DocShadow wrote:
Ratl wrote:
If the cause is the fuel pump pressure, then eliminating the pump would work. If it's the pump though, wouldn't it be overflowing all the time?
Ratl.

The pump shuts off when it reaches a predetermined pressure ... that's why you normally hear it run for a bit when you turn the ignition on.

It may be that the pressure 'sensor' is faulty ... just speculating.

Doc

What I meant by it overflowing all the time is that if the fuel pump pressure sensor is screwed up and is running at too high a pressure all the time, it should be overflowing all the time. Right?

The Yami pump is set up funny. I assume it has a pressure sensor/switch and a timeout device of some kind also. When I was testing my pump for flow, I disconnected the fuel line at the carb and turned on the switch. It pumped for a few seconds and stopped without any back pressure. I had to either turn the switch on and off or barely hit the start switch to get it to pump again.

Mry75 has a good point. I have had a carb float on another bike leak on one side so that it wouldn't close properly, but that has to be really rare.

I've been thinking about this since yesterday. The only things that make sense to me are:

1. The float bowl needle valve and/or valve seat being dirty or damaged so that they leak.

2. The fuel 'boiling' in the fuel line, causing enough pressure to push past the float bowl valve.

Everything else should be pretty rare don't you think?

Well you might be onto something with the pressure switch.
Yami tested the pump today, in spec. Nothing else.
But I found a cure! If I run with Makcap, it don't puke, soon as we split up it started puking about 2 sec after each start up. Only when I did not run bowl dry. Took my Desert Dawgs off, may have made some difference.

I have to believe it a mechanical problem somewhere. If it was heat alone why wouldn't all R's do it. Mine only does it once in a while, yet it's hot every time I ride it. I am leaning towards faulty needle valve or fuel pump pressure. It's gonna be a long hot summer, so I need to do something, just not sure what!

Ok just got back from a very grueling 500+ mile run through many elevations and heat.
Here's what I figured out.
It still pukes.
It pukes less when I try to shut fuel off before I land. That about cures the small after puke.

Now working on the re start (Cold or hot) puke.
If you can leave some fuel in the bowl for a startup.
BUT when you start it, don't just turn on the fuel I found it will still do the Throwup puke. (Lots of gas) No, start, let it run a bit and S-l-o-w-l-y turn the fuel on. I found somehow that works, DOC can explain why I am sure. I think if gives the float a chance to stabilize. But I only got like 3 serious pukes in 700 miles and it was plenty hot! I climbed like a total of 24000 ft of elevation in 500 miles. (According to GPS)
So someone else try my method and let us know what it does for ya.

MS1700 wrote:
Well you might be onto something with the pressure switch.
Yami tested the pump today, in spec. Nothing else.
But I found a cure! If I run with Makcap, it don't puke, soon as we split up it started puking about 2 sec after each start up. Only when I did not run bowl dry. Took my Desert Dawgs off, may have made some difference.
Glad to hear you roadie plays well with others LOL Just back from a long run myself and didn't even need a beer can this time. Thanks bud for the assists the other day.

Puking is driving me nuts. It is heat related and I thought maybe altitude related (barometric pressure difference) until I started reading the posts. I did not notice this problem when I lived in So. Cal. When I moved to CO is when I noticed it. It could be related to gas blend differences. It does not seem to be related to octane grades. Talking to dealers indicated that it was not uncommon and one said ‘we just live with it’. I refuse since it messes up my bike, leaves an ugly mess on ground, and is a fire hazard. My Road Star is very clean and well maintained. Very embarrassing when you are next to Hogs pumping gas on the ground and flooding out. The carb floats, settings, etc., have been adjusted umpteen times. It is better but not cured. I have filed a complaint with the National Highway Traffic Safety Administration at http://www.nhtsa.dot.gov. It was simple and if everyone who has a puking problem would do the same, Yamaha would be forced to do something. Feel free to copy and paste my complaint.

“Fuel (gasoline) is sprayed from rear port of carburetor. As much as 2 oz. may be emitted and sprayed on hot exhaust pipes and engine. The fuel is immediately vaporized. This only seems to occur when the engine is hot, then shut off and allowed to sit for approximately 15 minutes. It does not spray liquid gas if immediately started or if allowed to cool. First reported in August 2008. Problem is frequent.”

The posted threads are excellent and many good ideas as to cause presented, but I think this needs an engineering approach by Yamaha to identify the cause and come up with a fix. The threads make me feel better in that I am not the only one, but does not solve the problem.

I am now stopped from pursuing this further with the dealer or Yamaha. Seems like the guy I bought my Road Star from removed the CA emissions stuff specifically the charcoal canister. (Reference my Wanted ad in Classifieds). That leaves me without an argument for now, but I do not believe that is true with all of you who have this problem.

Recommend all who have this problem file a complaint with NHTSA.

Just a quick thought. Like I said before, I ride in some hot weather and I"m not what you'd call gentle with my bike, but I've not had this problem. Yesterday was two-up in 85 degrees all day, with frequent stops in the city. I was wondering if how you start your bike would have an effect. Do you just push the start button, or do you crack the throttle as you start. I always crack the throttle a lil. Could it be that the pump just floods it out if the engine doesn't turn over fast enough to use what it's being fed? Just a thought.

Thanks for your response. I should have stated the fact that one does not usually have to start the engine. Turn on the ignition and you can hear the fuel pump and then watch raw gas spew out. Don't know where you are from but I am beginning to lean more toward differences in gas blends across the country. Some do not seem to have this problem and I did not notice it in CA but after I moved to CO

Mry75 wrote:
Just a quick thought. Like I said before, I ride in some hot weather and I"m not what you'd call gentle with my bike, but I've not had this problem. Yesterday was two-up in 85 degrees all day, with frequent stops in the city. I was wondering if how you start your bike would have an effect. Do you just push the start button, or do you crack the throttle as you start. I always crack the throttle a lil. Could it be that the pump just floods it out if the engine doesn't turn over fast enough to use what it's being fed? Just a thought. No,its only when the engine is really hot ,as stated you do NOT have to start the bike for this to happen!! It's almost like the fuel pump should have a temp. sensor to compenste for that...

I'm sure if it was heat caused I'd've had a problem with it and I can't imagine how the gas would cause it. I'm sure curious to find out what it's all about, now. Maybe you should suggest the dealer swap out the pump and then the carb with known good units. Or maybe swap with a friend that isn't having this problem. That would narrow it down so that you knew for sure where the problem stems from. I did have an old '64 Buick that would do the same thing. I KNOW it was the float that caused that to flood out on me. It would puke out the throttle shaft and all over the intake. It did seem to do it worse on hot days. I would tap the float bowl with the handle of a screwdriver to unstick the float or it would just keep running till the line emptied out. I changed floats and needles in that old car and it still gave me fits. I just swaped some used carb parts I had, I never did properly rebuild the carb. Come to think of it, my old Harley did it once too. I'd been to a party in a dusty field and got dirt in the needle/seat to the point I could'nt even get the bike to start again. I pulled the line and shot a lil carb cleaner right on the needle/seat to get it started again till I could get home. I'll put my money down on the float assembly. Just my 2 cents.